The benefits of regular aerobic exercise have been well established and accepted. However, due to time constraints, inclement weather, and other reasons, many people are prevented from outdoor aerobic activities such as walking, jogging, running, and swimming. As a result, a variety of indoor exercise equipment has been developed for aerobic activity. It is generally desirable to exercise a large number of different muscles over a significantly large range of motion so as to provide for balanced physical development, to maximize muscle length and flexibility, and to achieve optimum levels of aerobic exercise. It is further advantageous for exercise equipment to provide smooth and natural motion, thus avoiding significant jarring and strain that can damage both muscles and joints.
While various exercise systems are known in the prior art, these systems suffer from a variety of shortcomings that limit their benefits and/or include unnecessary risks and undesirable features. For example, stationary bicycles are a popular exercise system in the prior art; however, these machines employ a sitting position that utilizes only a relatively small number of muscles, through a fairly limited range of motion. Cross-country skiing exercise devices are also utilized to simulate the gliding motion of cross-country skiing. While cross-country skiing devices exercise more muscles than stationary bicycles, the substantially flat shuffling foot motion provided by the ski devices limits the range of motion of some of the muscles being exercised. Treadmills are still a further type of exercise device in the prior art. Treadmills allow natural walking or jogging motions in a relatively limited area. A drawback of the treadmill, however, is that significant jarring of the hip, knee, ankle, and other joints of the body may occur through use of this device.
Another type of exercise device simulates stair climbing. Such devices can be composed of foot levers that are pivotally mounted to a frame at their forward ends and have foot-receiving pads at their rearward ends. The user pushes his/her feet down against the foot levers to simulate stair climbing. Resistance to the downward movement of the foot levers is provided by springs, fluid shock absorbers and/or other elements. These devices exercise more muscles than stationary bicycles; however, the rather limited range of up-and-down motion utilized does not necessarily exercise the user's leg muscles through a large range of motion. Further, the substantially vertical reciprocating motion of such stair climbing exercise machines can result in the application of undesirable impact loads to the hips, knees, and ankles of the user. In addition, the up and down reciprocating motion can induce a hyperextension of the knee. One attempt to reduce such loads in the prior art includes adding cushioning to the pedals of the stair climbing exercise machines.
Another drawback of existing stair climbing exercise machines is that such machines enable a user to take very small rapid steps during use. Such motion does not take the larger leg and gluteus muscles through large enough displacement to result in a significant cardio exercise. Rather, such smaller, faster stepping motions focus more on the generally undesirable anaerobic power system and not the desired aerobic endurance system.
A further limitation of a majority of exercise systems in the prior art lies in the limited types of motions that they can produce. A relatively new class of exercise devices is capable of producing generally elliptical motion that better simulates the natural stride of a person. Such exercise systems create elliptical motion, as referred to herein, when the path traveled by a user's feet while using the exercise system follows a generally ellipse-shaped path of travel. Elliptical motion is much more natural and analogous to running, jogging, and walking than the linear-type, back and forth motions produced by some prior art exercise equipment; however, devices that create an elliptical motion are generally limited to analogizing to running, jogging, and walking motions.
What would thus be desirable is an exercise device that provides for smooth natural action and exercises a relatively large number of muscles through a large range of motion. It would be further desirable for an exercise device to produce a user selectable raised, or highly angled, generally elliptical motion that simulates natural climbing or stepping motion. It would be further desirable for an exercise device to provide a relatively higher Relative Perceived Exertion (RPE) relative to the elliptical machines of the prior art. It would be further desirable for an exercise device to exercise muscles that are not exercised by elliptical machines of the prior art. It would also be advantageous to provide an exercise machine that allows for simulation of a stepping or climbing motion without allowing for the use of undesirable small rapid stepping movements.